1. Field of the Invention
The present invention relates to an image test apparatus, an image test system, and an image test method, and in particular, relates to a technology for diagnosing an apparatus based on an image test result.
2. Description of the Related Art
Conventionally, inspection of printed materials has been performed manually. However, in recent years, apparatuses that perform the inspection as post processing of offset printing are increasingly used. In such inspection apparatuses, first, a good-quality image is manually selected and loaded from among read images of printed materials, and a master image used as a reference is generated. Then, in the inspection apparatus, corresponding portions between the generated master image and the read image of the printed material used as a test object are compared with each other, and a defect of the printed material is determined based on the degree of a difference.
However, non-impact printing apparatuses, such as electrophotographic printers, that have recently become popular, have advantages in handling small-lot printing, and cope with a lot of cases, such as variable printing, in which different contents are printed for different pages. Therefore, unlike the offset printer, it is not effective to generate a master image from printed materials and use the master image as an object for comparison. To cope with this, it may be possible to generate a master image from print data. With this configuration, the variable printing may be handled effectively.
As an image test process as described above, a predetermined threshold is set for the degree of the difference as described above, that is, for a result of pixel-by-pixel comparison between an image obtained by reading an output sheet and a master image generated based on print data after positional alignment and size adjustment between the images are completed, and then whether or not there is a defect in the printed material is determined.
Alternatively, as a method to collect pieces of information available to determine a defected portion of an inner part of the image forming apparatus, an image forming apparatus extracts defects of images output on recording media, such as sheets of paper, and generates information by accumulating defects for each of the positions of the images for the determination (see, for example, Japanese Laid-open Patent Publication No. 2005-205682).
However, Japanese Laid-open Patent Publication No. 2005-205682 only discloses that a difference value accumulated for each pixel is used as the information for the determination performed by an operator. Therefore, the operator needs to perform final determination one after another, which becomes a burden on the operator. Namely, with only the technology disclosed in Japanese Laid-open Patent Publication No. 2005-205682, the determination of degradation of the apparatuses depends on the operator's determination capability, so that the degradation of the apparatuses may not be determined in a preferred manner. In addition, the above-mentioned problems can be occurred not only in case where an image is formed onto a sheet of paper but in case where an image is formed onto any of recording media other than the sheet of paper, for example, a film.
In light of the circumstances as described above, there is a need to enable determination of degradation of apparatuses based on a result of an image test, in which an image obtained by reading an output result of image formation is compared with a master image.